Common types of solar installations for generating electricity from solar energy systems include a stand-alone solar array with a back-up generator set, and a grid-connected system. A typical solar installation is generally comprised of a photovoltaic (PV) array, a combiner box, a DC/AC inverter, and a main electrical panel. The PV array is comprised of a plurality of PV modules that capture sunlight as direct current (DC). The PV modules are commonly connected into an electrical string to produce the desired voltage and amperage. The resulting wires from each string are routed to the combiner box. The electric output wires of the PV modules are wired together in the combiner box in order to get the voltage and current required by the DC/AC inverter. The DC/AC inverter converts direct current (DC) into alternating current (AC) that is provided to the main electrical panel. A DC disconnect switch is provided to disconnect the combiner box from the input of the DC/AC inverter, and an AC disconnect switch is provided to disconnect the main electrical panel from the output of the DC/AC inverter. In a typical solar installation, circuit protection devices are found in the combiner box, the DC/AC inverter and the main electrical panel.
Generating electricity from solar energy is generally a reliable process. However, any type of solar power generation system is vulnerable to fault currents or lightning. Circuit protection devices (e.g. fuses and surge protective devices) are effective ways of protecting the wiring and electrical equipment in a PV system. For example, fuses are used to protect cables between strings of modules from overcurrent damage. The faulty circuits are isolated allowing the PV system to continue generating power.
The continued development of PV systems has created a growing use of fuses to provide overcurrent protection for equipment and conductors (e.g., cables) associated with generation and distribution of solar power. While PV systems are designed to achieve maximum efficiency, fuses typically have power losses ranging from a few watts to near 10 watts. Accordingly, there is a need for a circuit protection device having lower power losses in order to provide higher efficiency in PV systems.
The present invention provides a circuit protection device that provides improved power efficiency in PV systems.